Conventionally, a swashplate type compressor is used in systems such as an air conditioning system of an automobile. According to a known swashplate type compressor, the transmission of motive power is carried out, as a swashplate rotates and a piston reciprocates, thereby suctioning, compressing and discharging the gas. The swashplate is usually composed of aluminum or iron alloy. The shoes, which make slideable contact with the swashplate when it rotates, are composed of iron or copper alloys. The metal on metal contact at the shoe and swashplate interface requires special precautions to be taken in order to prevent undue wear and possible seizure of the shoe with the swashplate. A good countermeasure to this problem has been to apply lubricious coatings on swashplates.
Polymer based coatings have been suggested for coating aluminum swashplates. U.S. Pat. No. 5,655,432 treats a swashplate with a coating of a mixture of cross-linked polyfluoro-elastomer bonded directly to the aluminum, a lubricious additive and a load bearing additive like boron carbide. The part is masked to apply the coating in only certain areas. Sho 58-129646 discloses a swashplate coated with a solid lubricant such as boron nitride, fluorine resin solidified with resin. It also discloses coating with soft metals like tin and lead. Polymer based coating, while providing excellent friction reduction and seizure resistance at dry condition, have less than desirable wear resistance (durability) due to the physical characteristics of the polymers. That is, they are soft compared to the counterparts they contact, normally ferrous metals, and become even softer at higher temperatures.
Metal coatings are commonly used to treat swashplate surfaces. For example, U.S. Pat. No. 5,056,417 treats a swashplate body with a surface coating layer made of tin and at least one metal selected from the group consisting of copper, nickel, zinc, lead and indium. U.S. Pat. No. 5,864,745 discloses flame sprayed copper based materials which may include lead useful to coat swashplates. Bronzes with lead have high load carrying capability and anti-seizure resistance making them suitable for anti-wear applications. Eliminating lead from coating materials, however, has been the focus of research in many industries due to environmental and health awareness. I have now surprisingly found a new lead-free copper-based coating material which has outstanding wear properties and overcomes deficiencies of prior art coatings.